[unreadable] [unreadable] Homelessness is a significant problem plaguing; American cities and homeless substance abusers face increased risks. Homeless, gay and bisexual male substance abusers (HGMSA) suffer 80% HIV seroprevalence, engage in the sex trades and resist treatment for substance abuse. For almost 30 years, the Van Ness Recovery House (VNRH) has been providing treatment services to HGMSAs in Hollywood, CA. In 1994, VNRH began providing HIV prevention services to non-treatment seeking HGMSAs through the VNPD, its prevention division. Because only 0.25% of HGMSAs at VNPD enter substance abuse treatment, VNRH, our community partner, identified overcoming HGMSAs resistance to entering treatment as a major strategic goal. To help them meet their goal, we seek to apply voucher-based reinforcement therapy (VBRT), a treatment with proven clinical efficacy, to non- treatment seeking, high-risk, homeless substance abusers, with increasing treatment entry as the goal. We will assess the efficacy of VBRT in motivating non- treatment seeking HGMSAs to enter substance abuse treatment and determine the effectiveness of VBRT by evaluating whether VBRT for HGMSAs can be financed and sustained by community donations. A controlled trial will randomize 144 HGMSAs at VNPD to either VBRT or control groups (72/group) for 24 weeks, with planned follow up at 7, 9 and 12 months from randomization. The VBRT group will earn vouchers in exchange for each step they take toward entering, free substance abuse treatment. Vouchers will be redeemable for goods located in an on site exchange stocked with community donations. The control group will have the same access to free treatment as the VBRT group, but completing treatment entry steps will not be reinforced. We will measure primarily the proportion of participants entering drug treatment, the number of steps taken towards treatment entry and the sustainability of a community-financed VBRT program. We will be among the first to apply VBRT to non-treatment seeking individuals as well as to integrate VBRT into a well-established prevention program with a harm reduction philosophy. Our reinforcement contingencies will shape behavior towards the goal of treatment entry, using a basic operant tenet that has not received sufficient attention. Stocking our on site store with community donations takes a step towards making our VBRT self-sustaining. Overall, our proposed research has the potential to have a significant impact on the public health of the Los Angeles gay and bisexual community. If VBRT is efficacious for motivating non-treatment seeking HGMSAs in a community-based prevention program to enter substance abuse treatment, established prevention programs may modify their approaches to include contingency management, and use it to address the staggering public health problems HGMSAs face on a daily basis. Moreover, we will discover whether financing and sustaining a voucher program for HGMSAs through donations from the local community and private sponsors is feasible. If it is, other prevention programs may adopt our community-sponsored VBRT strategy, helping to remove a major obstacle to disseminating a highly efficacious intervention for substance abuse. [unreadable] [unreadable]